Wednesday, November 13, 2013

Hubble did not convince Einstein

It has become a popular belief that Albert Einstein abandoned his static universe when, on a visit to Pasadena in January and February 1931, Edwin Hubble showed him the redshifted nebular spectra and convinced him that the universe was expanding, and the cosmological constant was superfluous. “Two months with Hubble were enough to pry him loose from his attachment to the cosmological constant” is just one example of such statements [Topper 2013]. There are variations of the theme, but the essence remains the same: Hubble personally convinced Einstein that the universe was in a state of expansion.

The present investigation shows that this stereotype misses the truth by a large margin. ...

The available documentation strongly suggests that Einstein’s reluctant conversion began in Cambridge, when in June 1930 Eddington confronted him with the fact that the static Einstein-model was unstable. In addition, Eddington certainly informed Einstein about de Sitter’s switch of allegiance to Lemaître’s expanding universe, and that the dynamical universe had received strong observational backing from Hubble’s publication of 1929, which de Sitter had verified in 1930.

When in December 1930 Einstein finally followed a long standing invitation of Millikan to visit Caltech, he already knew about Hubble’s observational discoveries and Lemaître’s hypothesis of an expanding universe, and he knew that Caltech’s Tolman was involved in the cosmological debate. All this is clear from his January 2, 1931 New York Times interview. There is no evidence that Hubble and Einstein indulged in any profound discussions, which would have influenced the latter’s cosmological concepts.

The available information strongly contradicts a popular cliché, which claims that Einstein was converted to the expanding universe by Hubble, when he showed him his observations in January 1931.

I am not sure why is matters what Hubble said to Einstein. The discovery of the expanding universe was by Lemaître and others.